Bifurcation stent delivery catheter assembly and method

ABSTRACT

A stent delivery system is disclosed for delivering and deploying a radially expandable stent at a strategic orientation and location in a body vessel. The delivery system includes an elongated flexible tubular shaft sized suitably for insertion into the body vessel. A stent deployment assembly includes a distal transition portion supporting a dilator device adapted for radial expansion about a longitudinal axis of the deployment assembly from a non-expanded condition to a radially expanded condition. The dilator device is configured to support the stent thereon in the non-expanded condition and in predetermined orientation relative the deployment assembly. A rotational clutch assembly rotatably mounts the transition portion to a distal portion of the tubular shaft such that the deployment assembly is substantially torsionally isolated from the tubular shaft, about a longitudinal axis of the clutch assembly. This enables the stent deployment assembly to rotate substantially independently of the tubular shaft for strategic orientation of the dilator device during advancement through the body vessel.

RELATED APPLICATION DATA

The present application claims priority under 35 U.S.C. §119 to U.S.Provisional Application Ser. No. 60/684,613, naming Von Oepen et al asinventors, filed May 24, 2005, and entitled BIFURCATION STENT DELIVERYCATHETER ASSEMBLY AND METHOD, and U.S. Provisional Application Ser. No.60/736,637, naming Von Oepen et al as the inventors, filed Nov. 15,2005, and entitled the same, both of which are incorporated herein byreference in their entirety and for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to catheters and systems usedfor delivering devices such as, but not limited to, intravascular stentsand therapeutic agents to sites within vascular or tubular channelsystems of the body. More particularly, it relates to delivery cathetersand systems for delivering stents to bifurcated vessels.

BACKGROUND OF THE INVENTION

A type of endoprosthesis device, commonly referred to as a stent, may beplaced or implanted within a vein, artery or other tubular body organfor treating occlusions, stenoses, aneurysms or dissections of a vesselby reinforcing the wall of the vessel or by expanding the vessel. Stentsare normally placed to scaffold the vessel and avoid elastic recoilafter angioplasty. Another reason for applying a stent is it to treatdissections in blood vessel walls caused by balloon angioplasty of thecoronary arteries as well as peripheral arteries and to improveangioplasty results by preventing elastic recoil and remodeling of thevessel wall. Two randomized multicenter trials have shown a lowerrestenosis rate in stent treated coronary arteries compared with balloonangioplasty alone (Serruys, P W et al. New England Journal of Medicine331: 489-495, 1994, Fischman, D L et al. New England Journal of Medicine331:496-501, 1994). Stents have been successfully implanted in theurinary tract, the bile duct, the esophagus and the tracheo-bronchialtree to reinforce those body organs, as well as implanted into theneurovascular, peripheral vascular, coronary, cardiac, and renalsystems, among others. The term “stent” as used in this Application is adevice that is intraluminally implanted within bodily vessels toreinforce collapsing, dissected, partially occluded, weakened, diseasedor abnormally dilated or small segments of a vessel wall.

One common procedure for intraluminally implanting a stent within a bodyvessel is to first dilate the relevant region of the vessel with aballoon catheter. Subsequently, a delivery catheter, such asPercutaneous Transluminal Coronary Angioplasty (PTCA) Catheterscontaining a dilator at the distal end thereof, is applied to transporta stent to the lesion site, and to deploy the stent in a position thatbridges the affected portion of the vessel. The expanded stent providesscaffolding to the lumen that allows adequate blood flow within thelumen. These delivery catheters typically include a relatively longflexible shaft (e.g., normally about 145 cm in length that is sized tobe percutaneously inserted into the vessels) with a dilator or stentdeployment assembly at the distal end of the shaft that carries thestent.

During any such catheterization and interventional procedures, includingfor example angioplasty and/or stenting, a hollow needle is initiallyapplied through a patient's skin and tissue to facilitate advancement ofthe catheter shaft through the target vasculature. As is often the case,however, the catheter shaft may need to be inserted into vessels havinga relatively tortuous path leading to the lesion site. Since it can bedifficult to steer many types of catheters, guidewires are applied tofacilitate advancement of the catheters through the vessel. Guidewiresare typically formed from a very small diameter metallic wire having aflexible tip that can be rotatably controlled to some degree. Theoperator shapes the tip of the guidewire by bending it depending on theanatomy of the vessel. Since the guidewire body is transmitting torquevery well, the tip of the catheter can be steered through the anatomy ofthe patient. Furthermore, steerable guidewires have been developed whichallow the operator to deflect the tip of the wire actively in thevasculature of the patient. The ability to rotatably control the tip isimportant in that the guidewire can be steered to access a desiredlocation through a potentially tortuous path such as the vasculature.

Once the guidewire is advanced through the needle and into the patient'sblood vessel, the needle is removed. An introducer sheath is thenadvanced over the guidewire into the vessel, e.g., in conjunction withor subsequent to a dilator. The catheter or other deployment device maythen be advanced through a lumen of the introducer sheath and over theguidewire into a position for performing a medical procedure. Thus, theintroducer sheath may facilitate introducing various devices into thevessel, while minimizing trauma to the vessel wall and/or minimizingblood loss during a procedure.

In some applications, the targeted region of a vessel may be at alocation where the vessel bifurcates. For example, in cases where plaquehas developed in the region of a vessel bifurcation, it may be desirableto perform angioplasty, atherectomy, and/or stenting in one or all ofthe affected vessels. In general, it is very important to preserve theside branch and the main branch of the bifurcation. In some occlusions,it might occur that during the dilation, plaque will be shifted from thetreated vessel to the non-treated vessel, and will then occlude thatnon-treated vessel. This effect is known as the “snowplow” effect. Toenable physicians to reaccess the vessel that has been affected by the“snowplow” effect, most physicians prefer to place a guidewire in thenon-treated branch as well. If the non-treated vessel is occluded duringthis procedure, the guidewire positioned in the non-treated vessel willfunction as a guiding element, and will allow the advance of anothercatheter to reopen that vessel. In other applications, it may bedesirable to insert a bifurcation stent specifically dedicated to treatlesions at a vessel bifurcation.

In the recent past, several commercially available bifurcation stentshave been developed that treat bifurcation lesions. By way of example,common alternatives to bifurcation lesion stenting include the ElectiveT technique, the Provisional T Technique, the Coulotte Technique, the VTechnique and the Crush. In addition, dedicated bifurcation systems likethe Frontier and AST Systems have been developed. While thesebifurcation stent designs have encountered varying degrees of success,one major problem associated with all bifurcation systems is that thedelivery and deployment of the stent, relative to the side branch, isextremely difficult. This is due primarily to the difficulty in properlycontrolling the orientation, alignment and position of the stentdeployment assembly relative to the main branch and side branch of thebifurcated vessel.

During advancement of the catheter shaft along the predisposedguidewire, the stent deployment assembly, which supports and transportsthe stent in a collapsed state, is not rotatably controlled. Hence, itis likely necessary to rotate and reorient the distal delivery assemblyabout its longitudinal axis since the bifurcation stent must be properlyaligned relative to the side branch before deployment. Transmitting acontrolled rotation to the distal end of the catheter over the length ofthe flexible catheter shaft, however, is nearly impossible. Due in partto the complex anatomy of a coronary artery, the flexible catheter shaftwill not adequately transfer torque to the dilatory. Although a proximalportion of the delivery catheter, which often includes a relativelyrigid material such as a hypotube or a polymeric tube with a stiffeningwire, can reasonably transmit torque, the more distal portions of theflexible catheter shaft cannot. Typically, the elongated, flexiblecatheter shaft will just rotate at the proximal portion withouttransmitting such rotational displacement to the dilator in a consistentmanner.

Accordingly, there is a need for a stent delivery system with improvedalignment and orientation capabilities of the distal stent deploymentassembly for those stents (e.g., bifurcation stents) that requireprecise rotational alignment, about their longitudinal axis, relative tothe target vessel site.

SUMMARY OF THE INVENTION

The present invention is directed toward a stent delivery system fordelivering and deploying a radially expandable stent at a strategicorientation and location in a body vessel. The delivery system includesan elongated shaft, and a stent deployment assembly including a proximaltransition portion associated with a dilator device. The dilator deviceis adapted for radial expansion from a non-expanded condition to aradially expanded condition, and further configured to retain the stentin the non-expanded condition. A rotational clutch assembly is includedthat is configured to rotatably mount the transition portion to a distalportion of the elongated shaft such that the deployment assembly issubstantially torsionally isolated from the elongated shaft.

Accordingly, when two guidewires are disposed in a main branch and aside branch at a carina of a bifurcated body vessel, the relativelyfreely rotatable distal stent deployment assembly can be more easilyradially aligned about its longitudinal axis (i.e., with lessresistance). Consequently, as the elongated shaft is advanced along theguidewires through the body vessel, the stent deployment assembly isself-aligned with the side branch for strategic orientation anddeployment of the stent. Moreover, such relatively free rotationaldisplacement of the stent deployment assembly improves the ability tounwind and navigate through twists in the guidewires as the deliveryassembly is advanced along the wires.

In one specific embodiment, the clutch assembly is adapted to transmitcompression forces longitudinally along the distal portion of theelongated shaft to the deployment assembly during advancement of theelongated shaft through the body vessel, as well as transmit tensionforces during retraction of the shaft.

In another arrangement, the clutch assembly includes an inwardly taperedshoulder portion coupled to one of a distal end of the elongated shaftand a proximal end of the transition portion. The clutch assemblyfurther includes a neck portion extending from the tapered shoulderportion. The neck portion is formed and dimensioned for slidingrotational receipt into an opening at the other of the tubulartransition portion and the elongated shaft for rotational receiptthereof.

A flexible protective boot device, in another specific embodiment,extends circumferentially over the clutch assembly having one endsecured to the elongated shaft and an opposite end secured to thesupport shaft forming a fluid-tight seal while still enabling relativerotation between the elongated shaft and the deployment device.

In another aspect of the present invention, a first guidewire lumen isincluded that extends along at least a portion of the stent deploymentassembly. The first guidewire lumen is sized and dimensioned for slidingreceipt of a first guidewire disposed in the body vessel. A secondguidewire lumen or passage further extends along at least a portion ofthe stent deployment assembly, and terminates strategically along thedilator device of the stent deployment assembly. The second guidewirelumen or passage is sized and dimensioned for sliding receipt of asecond guidewire disposed in the body vessel. The second guidewire lumenor passage is offset from the first guidewire lumen such that duringadvancement along the first and second guidewires, the deploymentassembly will be caused to rotate into alignment with the position ofthe second guidewire relative the first guidewire.

The clutch assembly may include a pair of opposed contact elementsdisposed in opposed relationship to one another. One contact element isassociated with the elongated shaft while the second contact element isassociated with the transition portion. During advancement of theelongated shaft through the body vessel, the contact elements are movedinto compressive mutual contact with one another to transmit axialcompressive forces from the elongated shaft to the transition portion.In one particular embodiment, the clutch assembly includes a firstsupport tube associated with the elongated shaft, and a second supporttube associated with the transition portion. Each support tube includesa respective end portion substantially in opposed relationship to oneanother, and each end portion supporting one of the contact elements inopposed relationship to one another.

An elongated stiffening element may be included that extendssubstantially longitudinally the clutch assembly. One end of thestiffening element is disposed in a distal pocket defined in part by adistal end wall of the transition portion, and an opposite end of thestiffening element is disposed in a proximal pocket defined in part by aproximal end wall of the elongated shaft. During the advancement of theelongated shaft through the body vessel, one end of the stiffeningelement contacts the distal end wall and the opposite end of thestiffening element contacts the proximal end wall to transmit axialcompressive forces from the elongated shaft to the transition portion.

In yet another embodiment, the clutch assembly includes an outer tubularflexible member having a proximal end associated to the elongated shaftand a distal end associated to the transition portion. The proximal endand the distal end of the flexible member are configured to rotaterelatively freely with respect to one another about a longitudinal axisof the flexible member.

The clutch assembly further includes an inner tubular flexible memberdisposed substantially co-axially within the outer tubular flexiblemember. A proximal end of the inner flexible member is associated to theproximal tube segment and a distal end is associated to the distal tubesegment. The first guidewire passage, thus, extends continuously throughthe elongated shaft, the clutch assembly and the stent deploymentassembly. The proximal end and the distal end of the inner flexiblemember are configured to rotate relatively freely with respect to oneanother about the longitudinal axis of the outer flexible member.

In one particular configuration both the outer and inner tubularflexible members are wound structures having a plurality of coils. Arespective proximal end coil of the plurality of coils associated withthe elongated shaft and proximal tube segment, and a distal end coil ofthe plurality of coils is associated to the transition portion and thedistal tube segment, respectively.

Each wound member may include a fluid impermeable, cylindrical-shapedinner sealing member disposed adjacent to the respective tubularflexible member. A respective proximal end of each sealing member isaffixed to the proximal tube segment or elongated shaft in a fluid-tightmanner, and a respective distal end thereof is affixed to the distaltube segment or transition portion in a fluid-tight manner to preventfluid penetration therethrough.

Still another specific embodiment provides a standoff feature disposedbetween the inner tubular flexible member and the outer tubular flexiblemember. During a collapse of the outer tubular flexible member onto theinner flexible tubular member under a vacuum, the stand-off featurecooperates with the tubular flexible members to define at least onefluid communication channel extending longitudinally along the clutchassembly from a proximal end to a distal end thereof.

In one embodiment, the standoff feature includes a plurality oflongitudinally extending protrusions disposed radially about the innerflexible tubular member. Each protrusion extends radially outward in adirection toward the outer flexible tubular member. The protrusions maybe integral with the inner flexible member, but may also be provided bythe protective sealing member.

In still another arrangement, the standoff feature includes one or moreelongated wound members wound about a respective longitudinal axis.These are disposed between the inner flexible tubular member and theouter flexible tubular member. A respective longitudinal axis of the oneor more wound members is offset from the longitudinal axis of the innertubular flexible member.

In yet another embodiment of the standoff feature, one elongated woundmember is provided wound about the inner flexible tubular member. Thelongitudinal axis of the wound member is substantially co-axial with thelongitudinal axis of the inner tubular flexible member.

In another aspect of the present invention, a rotational clutch assemblyis provided for a stent delivery catheter for delivering and deploying aradially expandable stent at a strategic orientation and location in abody vessel. The clutch assembly includes a tubular transition portionhaving a distal end mounted to the dilator device. A proximal portion ofthe transition portion is rotatably coupled to the distal end of theelongated shaft at rotational joint for substantially free rotationabout a longitudinal axis thereof relative to the elongated shaft.Hence, the dilator device of the catheter is substantially torsionallyisolated from the elongated shaft. The clutch assembly further includesa pair of opposed contact elements disposed in opposed relationship toone another. One contact element is associated with the elongated shaftwith the second contact element being associated with the transitionportion. During advancement of the elongated shaft through the bodyvessel, hence, the contact elements are moved into compressive mutualcontact with one another to transmit axial compressive forces from theelongated shaft to the transition portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The assembly of the present invention has other objects and features ofadvantage that will be more readily apparent from the followingdescription of the best mode of carrying out the invention and theappended claims, when taken in conjunction with the accompanyingdrawing, in which:

FIG. 1A is a side elevation view, in cross-section, of a stent deliverysystem, as constructed in accordance with the present invention.

FIG. 1B is a front elevation view, in cross-section, of a stentdeployment assembly of the stent delivery system taken substantiallyalong the plane of the line 1B-1B in FIG. 11A, and illustrating theformation of a second guidewire lumen.

FIG. 2 is an enlarged, side elevation view, in cross-section, of aclutch assembly of the stent delivery system of FIG. 1A.

FIGS. 3 and 4 are a series of side elevation views, in cross-section, ofthe stent delivery system of FIG. 1A, being advanced through abifurcated vessel and illustrating use and alignment thereof.

FIG. 5 is a side elevation view, in cross-section, of another specificembodiment stent delivery system, illustrating the opposed support tubesthat provide axial stiffness.

FIG. 6 is a side elevation view, in cross-section, of the stent deliverysystem of FIG. 1A with a dilator device in an expanded condition.

FIG. 7A is a side elevation view, in cross-section, of another specificembodiment stent delivery system, illustrating the opposed support bandsmounted to the opposed support tubes that provide axial stiffness.

FIG. 7B is a side elevation view, in cross-section, of another specificembodiment clutch assembly of the stent delivery system, illustratingopposed contacting stoppers mounted to the opposed elongated shaft andthe transition portion of the stent delivery assembly.

FIG. 8 is a side elevation view, in cross-section, of another specificembodiment stent delivery system, illustrating the incorporation of aNitinol wire axial stiffener.

FIG. 9 is a side elevation view, in cross-section, of a bifurcatedvessel, and illustrating the typical geometry of two guidewires disposedin the bifurcated vessel.

FIG. 10 is a fragmentary, side elevation view, in cross-section, of theclutch assembly.

FIG. 11 is a fragmentary, side elevation view, in cross-section, ofanother specific embodiment clutch assembly of the present inventioncontaining a plurality of interlocking tube elements and a bellow-typeprotective boot.

FIG. 12 is a fragmentary, side elevation view, in cross-section, of analternative for the interlocking tube element clutch assembly of FIG.11.

FIG. 13 is an enlarged, side elevation view, of the plurality ofinterlocking tube elements for the interlocking tube element clutchassembly of FIG. 11.

FIG. 14 is a top plan view of a flatten pattern of a tube structure tofabricate the annular bushing of FIG. 15.

FIG. 15 is a front elevation view of an annular bushing for theinterlocking tube element clutch assembly of FIG. 11.

FIG. 16 is a top plan view of a flattened pattern of a tube structure tofabricate the interlocking tube elements for the clutch assembly of FIG.12.

FIGS. 17A-17E is a sequence of schematic, top perspective views of adilator device of the stent delivery system of the present invention,illustrating formation of the second guidewire lumen using a mandrel.

FIG. 18 is a schematic, top perspective view of a dilator device of thestent delivery system in accordance with the present invention,illustrating formation of the second guidewire lumen within a fold ofthe dilator device.

FIG. 19 is a side elevation view, in cross-section, of another specificembodiment stent delivery system illustrating positioning of a distalsegment of the second guidewire tube along the stent deploymentassembly.

FIG. 20 is a side elevation view, in cross-section, of another specificembodiment stent delivery system illustrating mounting of the first andsecond guidewire tubes to an exterior of the tubular shaft.

FIG. 21 is a fragmentary, side elevation view, in cross-section, ofanother specific embodiment stent delivery system showing passage of thetwo guidewire lumens internally through the clutch assembly.

FIG. 22 is a fragmentary, side elevation view, in cross-section, ofanother specific embodiment stent delivery system incorporating a longarm catheter.

FIG. 23 is a side elevation view, in cross-section, of another specificembodiment stent delivery system, incorporating an outer protective bootand a central stiffening wire.

FIGS. 24 and 25 are fragmentary, side elevation views, in cross-section,of another specific embodiment stent delivery system incorporating adouble arm catheter.

FIG. 26 is a side elevation view, in cross-section, of another specificembodiment stent delivery system illustrating the application of twoclutch assemblies.

FIG. 27 is a side elevation view, in cross-section, of another specificembodiment stent delivery system incorporating a torque-transmittingdevice.

FIG. 28 is a side elevation view, in cross-section, of another specificembodiment stent delivery system incorporating another specificembodiment torque-transmitting device.

FIG. 29 is a partial cross-sectional view of another specific embodimentof a clutch in accordance with the present invention.

FIGS. 30A to 30D are cross-sectional views of features that may beformed in the surface of the coating or sleeve disposed about the innerflexible member.

FIG. 31 is a partial cross-sectional view of one specific embodiment ofa clutch assembly in accordance with the present invention furtherincluding an additional inner flexible member.

FIG. 32 is a partial cross-sectional view of one specific embodiment ofa clutch assembly in accordance with the present invention furtherincluding an additional flexible member.

FIG. 33 is a fragmentary, top perspective view of another specificembodiment of the clutch assembly for the stent delivery system of FIG.29, axially staggering in position of the inner and outer clutchassemblies.

FIG. 34 is a fragmentary, side elevation view of the clutch assemblyembodiment of FIG. 33.

FIG. 35 is an enlarged, fragmentary, side elevation view, in partialcross-section, of the outer clutch assembly of FIG. 34.

FIG. 36 is an enlarged, fragmentary, side elevation view, in partialcross-section, of the inner clutch assembly of FIG. 34.

FIG. 37 is a fragmentary, side elevation view, in cross-section, of theouter clutch assembly of FIG. 35.

FIG. 38 is a fragmentary, side elevation view, in cross-section, of theinner clutch assembly of FIG. 36.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the present invention will be described with reference to a fewspecific embodiments, the description is illustrative of the inventionand is not to be construed as limiting the invention. Variousmodifications to the present invention can be made to the preferredembodiments by those skilled in the art without departing from the truespirit and scope of the invention as defined by the appended claims. Itwill be noted here that for a better understanding, like components aredesignated by like reference numerals throughout the various figures.

Referring now to FIGS. 1-5, a stent delivery system, generallydesignated 40, is described that delivers and deploys a radiallyexpandable stent 41 (e.g., a bifurcation stent) at a strategicorientation and location in a body vessel 42. The delivery system 40includes an elongated shaft 43 sized suitably for insertion into thebody vessel 42. A stent deployment assembly 45 includes a tubular distaltransition portion 46 supporting a dilator device 47 adapted for radialexpansion about a longitudinal axis of the deployment assembly 45 from anon-expanded condition (FIG. 1, 3-4) to a radially expanded condition(FIGS. 5-8). The dilator device 47 is configured to support the stent 41thereon in the non-expanded condition, and in predetermined orientationrelative to the deployment assembly 45. The stent delivery system 40includes a joint device or clutch assembly 48 configured to rotatablymount the transition portion 46 to a distal portion 50 of the proximalelongated shaft 43 such that the stent deployment assembly 45 issubstantially torsionally isolated from the elongated shaft. This allowsthe dilator device 47 to rotate substantially independently fromelongated shaft 43 for strategic orientation of the dilator deviceduring advancement through the body vessel.

Accordingly, using a conventional two guidewire delivery system (FIGS.3, 4 and 28), the distal stent deployment assembly 45 (carrying thestrategically aligned stent) cooperates with the two guidewires 51, 52for rotational alignment thereof, about their longitudinal axis 60, asthe catheter system is advanced through the vessel along the guidewires.Briefly, one of the guidewires is disposed in a main branch 53 of thebody vessel 42, while the other guidewire is disposed in a side branch55 at a carina 56 using conventional deployment techniques such as thosedescribed in WO 01/30433 A1, published May 3, 2001, entitled “AGUIDEWIRE POSITIONING DEVICE”, and herein incorporated by reference inits entirety. Applying the two guidewires 51, 52 as an alignmentvehicle, the relatively freely rotatable distal stent deploymentassembly can be more easily radially aligned about its longitudinal axis(i.e., with less resistance) than in current delivery systems that wouldrequire rotation or torquing of both the stent deployment assembly 45and the elongated shaft 43. Consequently, as the elongated shaft 43 isadvanced along the guidewires 51, 52 through the body vessel, the stentdeployment assembly 45 is self-aligned with the side branch 55 (as willbe described in greater detail below in reference to FIG. 4) forstrategic orientation and deployment of the stent. Moreover, suchrelatively free rotational displacement of the stent deployment assembly45 improves the ability to unwind and navigate through twists in theguidewires as the delivery assembly is advanced along the wires.

A certain amount of wire crossing or wrapping cannot be avoided. Forexample, as shown in FIG. 9, at a vessel carina 56, the wires 51, 52will align according to the vessel geometry. Based upon the wire tensionand the position of the main branch 53 and diverging side branch 52, atthe very least, two wires crossing occur that many catheter systems areoften not capable of following the required rotation to navigatethrough. Hence, it is highly beneficial if the wire twisting is limitedto less than about 360°. Especially when the system is advanced in thecarina, then it has to be assured that the delivery system will allowthe stent to be correctly aligned with the geometry of the bifurcation.However, it is conceivable that all clutch embodiments of the presentinvention are capable of at least three full rotations in eitherdirection to negotiate twists and unwinding of the guidewires duringadvancement through a vessel. In fact, the rotation of the clutchassembly may only be limited by the elasticity of the protective boot orsleeve covering the same (e.g. boot 82 as will be described).

Referring back to FIG. 1, the stent delivery system 40 may primarily beprovided by a conventional balloon catheter apparatus with an elongatedflexible tubular shaft 43 composed of any conventional cathetermaterial. Such materials, by way of example, include stainless steel,nylon, PTFE, Pebax, and carbon fiber. The shaft length is typically inthe range of about 60 cm to about 300 cm, but may vary of coursedepending upon the application. Further, the shaft diameter is typicallyin the range of about 0.3 mm to about 7.0 mm, which is suitable forinsertion into most vessels of the coronary artery. Other dimensions maybe more suitable to use within other vascular or tubular systems of thehuman body. Such a diameter is also suitable to accommodate one or moreaccess lumens within the tubular shaft such as an inflation or fluidsupply lumen, as well as one or more guidewire lumens.

On the proximal end of the tubular shaft 43 is an adapter 57 mainly usedfor inflation/deflation. Preferably, the adapter 57 is elongated andsuitable for gripping and manual support, manipulation and operation ofthe delivery system and its components thereof.

While the clutch assembly 48 is primarily illustrated as positioned atthe distal end of the tubular shaft 43, it may be positioned moreproximally along the shaft 43 wherein the transition portion 46 isactually a more distal section of the tubular shaft 43. In general, asshown, however, the stent deployment assembly 45 is rotatably mounted tothe distal end of the tubular shaft 43, via clutch assembly 48. FIGS. 1and 2 illustrate that the stent deployment assembly 45 includes thetubular transition portion 46 having a proximal end coupled to theclutch assembly 48 and a distal end supporting the dilator device 47.The transition portion, which is preferably straight and relativelyshort, provides axial support to the dilator device 47 duringadvancement through the body vessel. Further, the diameter of thetransition portion 46 is substantially the same as that of the proximaltubular shaft 43.

A distal portion of the transition portion 46 can be tapered inwardly toform a nipple portion 58 that accommodates mounting of the dilatordevice 47 thereon. In other arrangements, the transition portion can bepart of the dilator device. For example, the transition device might bedilated to allow the dilator to be placed inside before connecting thecomponents. In other instances, the dilator device may be mounted usingan angled weld, an abutting weld or using inner and/or outerreinforcement tubes. The tubular transition portion 46 may also includeor act as part of an inflation lumen that communicates with the dilatordevice 47 for inflation thereof.

This dilator device 47 may be provided by any conventional systemcapable of selective radial expansion about a longitudinal axis of thedelivery assembly 45 between a non-expanded condition (FIGS. 1, 3 and 4)and the expanded condition (FIGS. 5-7). During advancement of the stentdeployment assembly 45 through the body vessel 42, the dilator device 47is of course maintained in a substantially non-expanded condition withthe stent (not shown) strategically mounted thereon in a collapsed orcrimped state.

The dilator device 47 can be provided by one of many radially expandabledelivery devices. In particular, however, the dilator device is anexpanding member-type device or the like that causes selective expansionof its elements, such as a balloon, an expandable mesh or a slithypotube, etc.

As mentioned, a clutch assembly 48 is disposed between the tubular shaft43 and the stent deployment assembly 45 near the distal portion of thestent delivery system 40. The clutch assembly 48 is designed to provideindependent, relatively resistance-free rotational displacement of thestent deployment assembly 45 generally about a longitudinal axis 60 ofthe clutch assembly, in relation to the proximal portion of the stentdelivery system 40. In accordance with the present invention, however,the clutch assembly 48, as mentioned, must also be capable oftransmitting axial compression forces from the tubular shaft 43 to thestent deployment assembly 45, as well as transmitting tension forces.Such compression force transmission by the clutch assembly 48 isnecessary to enable advancement of the stent deployment assembly throughthe body vessel 42. Accordingly, the clutch assembly 48 functions as adampener between the tubular shaft 43 and the stent deployment assembly45 such that the torsion forces inflicted upon stent deployment assemblyby the two guidewires during vessel advancement are not further resistedby the tubular shaft 43. Hence, the stent deployment assembly can moreeasily rotate about the longitudinal axis 60 to accommodate the positionof the guidewires (as will be explained in greater detail below) sinceit is rotationally isolated, via the clutch assembly 48, from torsionresistance generated by the tubular shaft 43. Further, the clutchassembly simultaneously transmits the axial compressive forces from thetubular shaft 43 to the stent deployment assembly 45 during saidadvancement and resists buckling due to resistive forces imparted by thebody vessel 42 during advancement.

As best shown in FIG. 2, the rotational joint device or clutch assembly48 is provided by “slip-fit” a male and corresponding female componentarrangement that provides both rotational displacement about thelongitudinal axis 60, as well as providing axial compression forcetransmission. In one specific embodiment, the proximal end of thetransition portion 46 includes an inwardly tapered shoulder portion 61that intersects a neck portion 62 that further extends proximally alongthe longitudinal axis 60 thereof. The neck portion 62 is substantiallycylindrical or may slightly taper inwardly. The diameter of the neckportion is smaller than that of the distal end of the tubular shaft bythe amount substantially equal to the tapered shoulder portion 61.

The corresponding female component of the clutch assembly 48 is providedby a receiving socket 63 formed at the distal end of the tubular shaft43. This distal receiving socket is sized for sliding slip-fit of theneck portion 62 in a manner provided substantially resistance-freerotation of the transition portion 46 about the longitudinal axis 60 ofthe clutch assembly 48. FIG. 2 best illustrates that the distal endportion of the tubular shaft 43 includes a proximal rim portion 65 thatdefines an opening into the receiving socket 63. The receiving socket 63of the clutch assembly 48 is further defined by a substantiallycylindrical interior wall 66 having a diameter slightly larger than thatof the mating neck portion 62 of the clutch assembly.

The diametric tolerance between the interior walls 66 of the receivingsocket 63 and the cylindrical exterior surface of the neck portion 62 issufficient to enable substantially resistance-free rotationaldisplacement of the neck portion in the receiving socket 63, while atthe same time providing sufficient lateral support should such supportbe required during catheter advancement through the vessel. To reducefriction between the contacting components, they may be coated with PTFE(i.e., TEFLON®) or include other types of lubricants, coatings, orlubricious materials. Such biocompatible lubricants and/or materials arewell known in the field and included herein.

In one specific embodiment, the clutch assembly 48 coaxially aligns thestent deployment assembly 45 with tubular shaft 43. Upon longitudinalreceipt of the neck portion 62 in the receiving socket 63, hence, thelongitudinal axis of the stent deployment assembly 45 is substantiallycoaxial with the longitudinal axis 60 of the clutch assembly 48, andwith that of the distal portion 50 of the tubular shaft 43. Such axialalignment is preferable to retain the small overall diametric footprintat the distal portion of the delivery system 40.

The clutch assembly 48 further includes a pair of opposed support tubes67, 68 that provide axial stiffening and stability, and to transmit theaxial compression forces during contact therebetween when the deliverysystem is in a compressive state. As best shown in FIGS. 1-6, a proximalsupport tube 67 is disposed and supported within the distal portion 50of the tubular shaft 43, and is generally positioned along thelongitudinal axis 60 of the clutch assembly. Similarly, an opposeddistal support tube 68 is disposed and supported within the proximalportion of the distal transition portion 46, and is generally positionedalong the longitudinal axis 60 of the clutch assembly as well. When theclutch assembly 48 is assembled where the neck portion 62 is slip-fitinto the receiving socket 63 of the tubular shaft 43, the distal end ofthe proximal support tube 67 is also slideably received through aproximal opening into the tubular transition portion 46 and into opposedco-axial relationship with the proximal end of the distal support tube68. Hence, during compression, such as during advancement of the tubularshaft 43 through the body vessel as shown in FIG. 3, the proximalsupport tube 67 axially contacts the distal support tube 68. Such axialcontact provides axial stiffening and stability, and transmits the axialcompressive forces urged upon the tubular shaft 43 to the stentdeployment assembly 45. However, when the clutch assembly 48 is not in acompressive state, such as shown in FIGS. 2 and 4, the opposed tubes 67,68 are not in sufficient axial contact, permitting the clutch assemblyto rotate about its longitudinal axis 60. The clutch assembly can alsorotate when the opposed tubes are in contact.

In one specific embodiment, as shown in FIG. 5, the distal end portion70 of the proximal support tube 67 tapers radially inward. When theclutch assembly is in a compressed state, this conical-shaped distal endportion 70 contacts the proximal end of the distal support tube 68,providing axial stiffness. Likewise, the proximal end of the distalsupport tube 68 may be tapered to permit contact with the distal end ofproximal support tube 67. In another configurations, as illustrated inFIGS. 1-4 and 6, a pair of contact washers 71, 72 or the like arefixedly disposed on the distal and proximal ends of the opposed supporttubes 67, 68. When the clutch assembly 48 is in a compressive state, theopposed contact washers 71, 72 axially contact one another to provideaxial stiffness, and enable the transmission of axial compressive forcesfrom the proximal support tube 67 to the distal support tube 68 (FIG.3).

In another specific embodiment, a set of bands 73, 75 are providedaround the opposed neck down portions 76, 77 of the correspondingsupport tubes 67, 68 (FIG. 7A). Similar to the contact washers, thesebands 73, 75 contact one another during a compressed state of the clutchassembly 48 to provide axial stiffness therebetween. Such bands 73, 75can be wholly or partially formed from a radiopaque material tofacilitate observation and positioning of the clutch assembly 48 usingfluoroscopy or other imaging systems. These support bands 73, 75 can becomposed of any suitable material, and even be made from cured adhesive.These bands 73, 75 can be crimped, glued, swaged etc. to the supporttubes.

Alternatively, as shown in FIG. 7B, a pair of contact or stoppers 74,74′ may be incorporated about the neck portion 62, and along theinterior wall 66 of the receiving socket 63. These stoppers 74, 74′ arepreferably metallic (e.g., RO Markers). The outer shaft 43 may beenlarged and shrinked over the metallic stopper 74, or the metallicstopper will be attached on the inside. A similar procedure will beapplied to attach the other metallic stopper 74′.

In still another specific embodiment that promotes axial stiffness, asshown in FIG. 8, an elongated wire 78 is disposed in a set of pockets80, 81 formed between the distal portion 50 of the tubular shaft and theproximal portion of the transition portion 46. These correspondingpockets 80, 81 extend circumferentially about the longitudinal axis ofthe clutch assembly 48, permitting rotation of the stent deploymentassembly 45 relative the tubular shaft. Alternatively, the wire may bepositioned central to the clutch assembly.

Upon compression of the clutch assembly 48, the opposed ends of the wire78 contacts the opposed ends of the pocket 80, 81 to provide axialstiffness. The wire 78 can be fixed at either one or both ends or simplybe free-lying within the pockets. The wire may be constructed fromNitinol, or any other metallic material that provides suitableflexibility and mechanical characteristics. Other material exhibitingsuch characteristics and properties may be utilized such as a carbon rodor the like.

In other configurations, the neck portion 62 and/or the shoulder portion61 of the clutch assembly 48 may simply abut or contact the interiorwalls 66 and/or the rim portion 65, respectively, of the transitionportion 46. Hence, when an axial driving force is urged upon the tubularshaft 43 during vessel advancement, the contact between the componentsof the clutch assembly 48 transmit the forces to the stent deliverydevice to further advance the same through the vessel.

It will be appreciated that while the clutch assembly 48 of the presentinvention is shown and described in the configurations of FIGS. 1-8 ashaving the neck portion 62 contained on the proximal end of the distaltransition portion 46 and the receiving socket 63 contained on thedistal end of the proximal tubular shaft 43, the mating components canbe easily reversed without departing from the true spirit and nature ofthe present invention. For example, as illustrated in FIGS. 10 and 22,the neck portion 62 extends distally from the tubular shaft 43, whilethe receiving socket 63 is at the proximal end of the distal transitionportion 46.

The clutch assembly 48 further includes a cylindrical shell-shapedprotective boot 82 or the like to provide a fluid-tight seal around theclutch assembly components (FIGS. 1 and 2). By affixing a proximalportion of the protective boot 82 to the outer or inner circumferentialsurface of the distal portion 50 of the tubular shaft 43, a fluid tightseal at the proximal end can be formed. Similarly, a distal portion ofthe protective boot 82 can be affixed to the outer or innercircumferential surface of the transition portion 46, forming anothercircumferential fluid tight seal. Collectively, the protective boot 82seals the clutch assembly components therein.

The protective boot may be bonded to the outer circumferential surfacesof the tubular shaft 43 and the transition portion 46 using anybiocompatible adhesive or weld material. For example, a transitionbonder or any other conventional bonding techniques can be applied suchas shrink tubes and hot air, jaw welding, RF welding, UV hardeningadhesive, laser welding, white light welding, etc. In another specificembodiment, as shown in FIG. 10, the proximal and distal ends of theprotective boot 82 may be embedded in a pair of mounting sleeves 83, 85that are mounted to the outer circumferential surfaces of the tubularshaft 43 and the transition portion 46.

In accordance with the present invention, since the ends of theprotective boot 82 are affixed to the transition portion 46 and thedistal portion 50 of the tubular shaft, the rotational displacement atthe clutch assembly 48 will be limited to such rotation afforded by thetwisting of the boot 82. Therefore, depending upon the size and fitment(e.g., excess looseness) of the protective boot 82, relative the clutchassembly 48, as well as the material properties of the boot, more orless axial rotation can be accommodated. A rotational displacement aboutthe longitudinal axis 60, in the range of between about 0° to about±720°, more preferably to about ±360°, and even more preferably to about±180°.

Generally, the selected boot material should not significantly transmittorque from the stent deployment assembly 45 to the proximal tubularshaft 43 during twisting. That is, a material should be selected thatwill not introduce any resistive torque in the direction opposite to therotation of the stent deployment assembly. Another important quality ofthe protective boot material is that it is fluid impervious. By way ofexample, this protective boot 82 may be formed of a biocompatible, fluidimpervious material, such as those composing balloon catheters. Further,with a sufficient wall thickness of about 10-100 microns, the protectiveboot will resist inflation during inflation of the dilator device shouldthey be in common fluid communication with one another. This thin walledboot enables free rotation of the stent delivery assembly.

Briefly, one technique to achieve the required rotational properties ofthe balloon is to slightly pressurize the balloon material (e.g., 1atm), and then twist the boot in an oscillatory manner (e.g., about0-1000 times, more preferably about 0-100 times, and even morepreferably about 0-50 times). This creates a plurality of small wrinklesin the boot material that facilitate rotation. This procedure should beperformed prior to the cutting of the “balloon” sleeves to the correctlength.

In another specific configuration, as shown in FIGS. 11 and 12, the bootdesign may be provided by a bellows-type balloon that permit axialrotation. In other instances, the balloon may be folded.

Referring now to FIGS. 11 and 13-14, another specific embodiment clutchassembly 48 is shown containing a plurality of interlocking tubeelements 86, 86′ that cooperate for rotational displacement about thelongitudinal axis 60. FIG. 9 shows elements 86, 86′ that are placed on astainless steel cable 87 (e.g., stranded wires), or a steel wire, aNitinol wire, polymeric “wire”, polymeric rod or any kind of reinforcedrods i.e. polymeric reinforced rods with Carbon, glass or boron etc.Opposed annular bushing 88, 89 couple the clutch assembly 48 to thecorresponding tubular shaft 43 and the transition portion 46.Preferably, although not limited to, the bushings 88, 89 are stainlesssteel, and can be produced from a single tube structure 135. FIG. 14shows a flat view of geometry of the bushings for illustration purposes.The preferred production method will be laser cutting but is not limitedto this. Instead of laser cutting other manufacturing procedures likemicro EDM, etching or any kind of micro-machining can be used.

The flat structure 135 shown in FIG. 14, is actually annular-shaped(FIG. 15) with three arms 136 and optional an additional stiffeningelement 137. The three arms 136 are bent inwards and connected to one ofthe stainless steel elements 86, 86′ that are sitting on the steel cable87 like pearls. Welding would be one sufficient connecting method butother methods like hot melt, soldering gluing etc. can be used as well.On each side proximally and distally one bushing will be connected. Theouter diameter of the bushing will fit the inner diameter of thesupporting tube 46 or the proximal tube 43. The bushings will beconnected to the tubing 46 and 43 by any kind of connecting method likewelding, shrinking gluing etc. To allow the bushings to fix in thetubing the distal end of the tube 43 and/or the proximal end of thesupporting tube 46 can be enlarged to allow the bushing to fit in.

In order to provide a smooth transition on both ends or individually onthe proximal or the distal end, a stiffening element 138 can be added atthe entrance and exit point of the guide wire (FIG. 11). At theselocations there will be no sufficient support since the guide wire isrunning on the outside of the catheter body.

This construction allows a maximum axial support of the catheter byhaving no limitation towards rotation. The resistance against rotationis minimal due to the PTFE or other low friction materials added to thechain construction. The clutch will be pressure sealed by a thin walledmember that is running over the clutch and will only add minimallimitation towards rotation.

to decrease the resistant of the thin walled boot 82 over the clutch,the boot can be constructed like a bellow, as mentioned above. Theadditional folds in the boot will further minimize the resistanceagainst torque.

The space between the arms of the bushings will be sufficient to allowfluid communication between the inflatable member and the proximal endof the catheter.

FIGS. 12 and 16 illustrate another specific embodiment having maximumaxial support by minimal friction against rotation. FIG. 16 shows a flatview of a tubing 140 that is cut in a certain pattern. The cuttingdesign allows the rings 141 to rotate against each other. The principleof this construction is a plurality of interlocking tube elements 142,143 that cooperate for rotational displacement about the longitudinalaxis 60. To prevent the elements 142, 143 from separating from oneanother, they will be placed over a PTFE or any other low friction tube.The interior of each element 142, 143 is to be a hollow construction toallow fluid communication between the inflatable member and the proximalend of the catheter.

Similar to the embodiment of FIG. 11, a pair of stiffening elements 144can be added to the tube construction either by cutting indirectly fromthe tube or connecting into the tube element by laser welding or anyother appropriate connecting method. As described above the stiffeningelement 144 will provide a smooth transition at the entrance and exitplace of the guide-wire.

The proximal and distal end of the rotation tube will be connected tothe supporting element 46 and the proximal tube 43. The distal end oftube 43 can be enlarged as well as the proximal end of the distalsupport tube 46 to fit the proximal and distal end of described rotationtube. In another embodiment the tubes 43 and 46 might fit directly tothe size of the rotational tube or might even be tapered down.

Referring back to FIGS. 3 and 4, in order to rotationally align thesubstantially independently rotating stent deployment assembly 45 (aboutlongitudinal axis 60) during advancement thererof along the guidewires51, 52, the delivery assembly includes a set of guidewire passages(e.g., the first guidewire passage 90 and the second guidewire passage91) that slideably receive the respective first and second guidewires51, 52. At least a distal passage segment 92 of the first guidewirepassage 90 extends centrally through the dilator device 47 generallyalong the longitudinal axis of the stent deployment assembly 45. Thedistal passage segment 92 of the first guidewire passage 90 is suitablysized for sliding receipt of a first guidewire 51 that is pre-advancedthrough the body vessel 42, typically through the main branch 53 asshown in FIGS. 3 and 4. In general, the distal passage segment 92 of thefirst guidewire passage 90 may be defined in part by a distal tubesegment 93 of a first guidewire tube 95 extending at least through theexpandable elements 96 (e.g., a balloon) of the dilator device 47.Hence, the first guidewire passage 95 and the distal passage segment 92may be for the most part lumens. The distal passage segment 92 of thefirst guidewire passage 90 terminates at the distal end of the stentdelivery device near its longitudinal axis thereof. A soft tip sleeve 97may be mounted to the distal end of the distal tube segment 93 of thefirst guidewire tube 95 to as is commonly done in stent delivery systemsin order to prevent vascular trauma during shaft advancement and tofacilitate access through the lesion, and optimize tracking of thecatheter.

In accordance with the present invention, the stent deployment assemblyalso includes a second guidewire passage 91 that extends in a directiongenerally adjacent to, although radially offset from, the firstguidewire passage 90. As shown in FIGS. 3 and 4, the second guidewirepassage 91 is also suitably sized for sliding receipt of a secondguidewire 52 as the delivery assembly is advanced through the bodyvessel 42. Typically, a second guidewire 52 is employed through the bodyvessel 42 in situations requiring greater rotational alignment anddeployment precision of the stent. In the examples illustrated herein,the second guidewire 52 is utilized to locate the side branch 55 of thebifurcated body vessel 42. As mentioned, a stent 41 loaded onto thedelivery assembly must be accurately aligned with the side branch 55 forproper deployment.

The second guidewire passage 91 may be formed and/or fabricated alongthe stent deployment assembly using many different techniques as will bedescribed below. One common physical characteristic, however, is thatthe second guidewire passage 91 extend under the collapsed stent 41 thatis mounted over the dilator device 47 (FIG. 1A), and that a distal endor guidewire exit 98 from the second guidewire passage 91 bestrategically positioned near or at the stent side branch port 103 ofthe collapsed stent 41. Briefly, the stent side branch port 103 willform the access port to the vessel side branch 55 when the stent isexpanded and deployed. For example, the guidewire exit 98 from thesecond guidewire passage 91 terminates at the fish-mouth of the stent41, radially offset from the first guidewire passage extending along thelongitudinal axis.

In the particular embodiments illustrated in FIGS. 1A, 1B, 3 and 4, thesecond guidewire passage 91 is defined by a plurality of channels 100formed between the exterior of non-inflated dilator device 47 and anunderside of the particular struts 101 of the stent 41, in the collapsedstate. Briefly, it will be appreciated that while the stent 41 is shownand illustrated more or less as a solid tube, the stent is actuallycomposed of conventional patterned cells and expandable struts 101similar to any other conventional stent.

Referring back to the configuration of FIGS. 1A and 1B, the secondguidewire passage 91 extends longitudinally along an exterior of thenon-inflated dilator device 47 in a direction substantially parallel tothe first guidewire passage 90. More particularly, as shown in FIG. 1B,the corresponding struts 101 defining the corresponding channel 100 eachinclude a smaller radius bend 102. It is notable, however, that anactually radius bend may not exist after the crimping process. Togetherwith the non-inflated dilator device, the aligned channels 100collectively define the second guidewire passage 91.

In accordance with the present invention, the position and off-setnature of the guidewire exit 98 of the second guidewire passage 91relative to the first guidewire passage, as well as the independent,substantially resistant-free rotation of the stent deployment assemblycollectively cooperate to self-align the dilator device 47 (and thestrategically mounted stent thereon) with the vessel side branch 55.

Once the stent deployment assembly 45 nears the target site (e.g., fromFIG. 3 to FIG. 4), where the first guidewire 51 and the second guidewire52 diverge and are more distinctively separated (e.g., where tip of thefirst guidewire 51 extends into main branch 53 while the tip of thesecond guidewire 52 extends into the side branch 55), the off-set of thesecond guidewire exit 98 from the first guidewire passage 90 togetherwith the substantially resistance-free rotation of the stent deploymentassembly 45, via rotational clutch assembly 48, facilitate rotationalalignment of the second guidewire passage 91 (about axis 60) toward thevessel side branch 55 (FIG. 4). In essence, as the stent deploymentassembly 45 advances and tracks along the guidewires near carina 56, thesecond guidewire 52 diverges away from the first guidewire that extendsdown the vessel main branch 53. At the side branch 55 (directly above asshown in FIG. 4), the divergence of the second guidewire 52 away fromthe first guidewire 51 pulls the stent deployment assembly 45 intorotational alignment with the vessel side branch 55. Since the clutchassembly 48 provides substantially resistance-free rotation of the stentdeployment assembly 45 about the longitudinal axis 60, it is more easilyand precisely aligned with the side branch 55 for delivery anddeployment of the stent.

When the stent deployment assembly 45 is advanced to the divergencebetween the first guidewire 51 and the second guidewire 52, furtheradvancement of the system through the body vessel 42 will generallycease. At this position, the guidewire exit 98 of the second guidewirepassage 91 will be rotationally aligned (about axis 60) with the vesselside branch 55 (aligned below in FIG. 4).

It will be understood, however, that the guidewire exit 98 of the secondguidewire passage 91 could be located nearly anywhere longitudinallyalong the stent 41. Accordingly, depending upon the desired length ofthe extension of the stent 41 past the carina 56 and into the mainbranch 53 (which in-part may be dictated by the occurrence and positionof any post branch lesion), the position of the stent side branch port103, and thus, the guidewire exit 98 can be located nearly anywherealong the stent during manufacture or with a dedicated device duringuse. For example, if a longer extension of the stent 41, past the carina56, is desired, the guidewire exit 98 can be positioned at a proximalportion of the stent 41. In contrast, by positioning the guidewire exit98 of the second guidewire passage 91 closer to the distal end of thestent 41, a shorter stent extension into the main branch 53 is provided.

Once aligned, the dilator device 47 can be selectively inflated forradial expansion from a non-expanded condition (FIGS. 1, 3 and 5) to anexpanded condition (FIGS. 5-8). Subsequently, the stent is expanded froma collapsed state to an expanded state for deployment in the bifurcationvessel. After expansion, the operator can decide how to proceed. Ingeneral, the guidewire 52 will be used to advance a second PTCA catheterinto the region of the bifurcation.

The second balloon catheter has to pass through the struts of the stent.Once in place, the second balloon catheter can be inflated to dilate theuntreated vessel. One advantage of this arrangement is that the deliverysystem of the first stent can remain in place even when an additionaltreatment is required.

After dilating the non-stented branch, the physician can further decidewhether they want to place an additional stent in the other branch. Theprocedure will be normally finished by using the kissing balloontechnique.

Briefly, while most types of bifurcation stents can be deployed in thismanner, the delivery assembly of the present invention is particularlysuitable for Provisional T type or fish-mouth stents, as aboveindicated. In this manner, the fish-mouth of the bifurcation stent 41can be accurately aligned with the side branch 55 so that the sidebranch is not, or is minimally, occluded by the stent in any manner.

Furthermore, it will be appreciated that the delivery assembly of thepresent invention may be applied in combination with other devices andtechniques that improve the precision and alignment of the deliverysystem with a bifurcated vessel. One such complementary system is thatdescribed in U.S. application Ser. No. ______, naming Von Oepen et al asinventors, filed May 4, 2006, entitled “GUIDEWIRE APPARATUS WITH ANEXPANDABLE PORTION AND METHODS OF USE”, and herein incorporated byreference in its entirety.

Turning now to FIGS. 17A-17E, the formation of the second guidewirepassage 91, in the embodiments of FIGS. 1-4, is illustrated. Initially,as shown in FIG. 17A, the expandable elements 96 of the dilator device47 are not folded. The expandable elements 96 are then folded using aconventional folding technique (i.e., as shown in FIG. 17C in thenon-inflated condition). The folded, non-inflated dilator device 47 isthen inserted into a partially expanded stent 41 (FIG. 17D).

For the specific embodiments of FIGS. 1-4, where the second guidewirepassage 91 is formed between the underside of the stent 41 and theexterior of the expandable elements 96 of the dilator device 47, amandrel 105 is inserted therebetween, as illustrated in FIG. 1 7E. Thismandrel duplicates the desired path of the second guidewire passage 91.A proximal portion of the mandrel 105 enters the proximal end of thestent 41, while a distal portion of the mandrel exits through the stentside branch port 103 (or fish-mouth) of the stent 41. The stent in theas-cut condition 41 is then crimped onto the dilator device 47, usingconventional crimping techniques, which forms the smaller radius bends102 as the stent struts 101 and the expandable elements 96 are pushedagainst the mandrel.

Upon removal of the mandrel 105, which incidentally may be performedjust prior to use, the second guidewire passage 91 is fabricated asshown in FIGS. 1A and 1B. In another configuration, the mandrel might beremoved and exchanged against a transport stylet. It will be appreciatedthat upon expansion of the dilator device and deployment of the stent41, the small radius bends 102 will be removed from the expandedstructure of the stent.

Alternatively, as illustrated in FIGS. 17B and 18, the mandrel 105 maybe placed within a fold 99 of the expandable elements 96, under theexterior surface of the dilator device. Consequently, when the mandrel105 is removed after conventional stent crimping, a second guidewirepassage 91 will be formed that extends generally through the fold andunder the exterior surface of the non-inflated dilator device.

In another specific embodiment, as shown in FIG. 19, the secondguidewire passage 91 may be defined by a dedicated second guidewire tube106 with a dedicated lumen. In this arrangement, a distal tube segment107 of the second guidewire tube 106 extends through the proximal end ofthe stent 41 and between the exterior surfaces of the non-inflateddilator device 47. To even advance the alignment of the delivery system,it might be beneficial to provide a second catheter tip that is advancedthrough the stent struts. When this additional catheter tip is advancedinto the side branch, it will facilitate the system to rotate in place.A distal end of the second guidewire tube, containing the guidewire exit98, is preferably positioned proximate to the stent side branch port103. Further, guidewire exit 98 of the distal tube segment 107 (alsosecond guidewire passage 91) may actually be coincident, inside, oroutside of the stent side branch port 103.

Similar to the formation of the second guidewire passage in theembodiments of FIGS. 1-4, the stent 41 may be crimped around the distaltube segment 107 of the second guidewire tube 106. Also similarly, thedistal tube segment 107 may be interwoven or folded into the inflationelements of the dilator device itself for securement.

As viewed in FIGS. 19 and 20, the portion of the distal tube segment 107of the second guidewire tube 106 extending adjacent the exterior of thedistal transition portion 46 is also secured thereto using conventionaltechniques, such as an adhesive 104 or welding technique. In anotherembodiment shown in FIGS. 21 and 22, a support sleeve or band 108 may beapplied affixing the distal tube segment 107 to the transition portion46. Such sleeves or bands may exhibit elastic characteristics thatresiliently couple a proximal portion of the distal tube segment 107 tothe fluid-tight port 118.

It will be appreciated that distal tube segment 107 of the secondguidewire tube 106 may be composed of a material that is capable ofmaintaining the integrity of the second guidewire passage 91 when beingcrimped against the dilator device 47, such as a crimping mandrel. Thematerial of this tube segment, however, must also be sufficientlyflexible to enable expansion of the dilator device 47 from thenon-expanded condition (FIG. 19) to the expanded condition (FIGS.20-24). Such materials include HDPE Polymide, PTFE, FEP, Polymideimpregnated with PTFE, POM and other low friction plastics.

During operable use, when the first and second guidewires 51, 52 arebeing advanced through the corresponding first and second guidewirepassages 90, 91 at the stent delivery assembly, the guidewires must bothspan or bridge across the rotatable clutch assembly 48 withoutinterfering with the resistance-free rotational movement thereof. In theembodiments of FIGS. 1-4, the first guidewire 51 emerges from the distaltube segment 93 through a first port 112 in the transition portion 46 ofthe stent delivery assembly 46. Similarly, the second guidewire 52emerges from a proximal end of a distal tube segment of the secondguidewire passage 91 thereof. As best shown in FIGS. 3 and 4, both thefirst guidewire 51 and the second guidewire 52 extend loosely across theclutch assembly 48.

In the embodiment of FIG. 3, the second guidewire 52 extends furtherback and alongside the tubular shaft 43 once it passes through thepassageway 91 of the stent delivery assembly. In another configuration(not shown), both the first guidewire 51 and the second guidewire 52 mayextends alongside the tubular shaft 43 and all the way back once itpasses through of the stent delivery assembly 45.

Alternatively, after bridging the clutch assembly 48, none, one or bothloose guidewires 51, 52 may subtend into a proximal passage segment 115,115′ of their respective guidewire passages 90, 91, and throughcorresponding second and third ports 113, 113′ extending into thetubular shaft 43 (FIG. 4). As shown in FIG. 3 (as well as theembodiments of FIGS. 5-7), for example, only one guidewire (e.g., thefirst guidewire 51) subtends into the tubular shaft 43, via the secondport 113. In another specific arrangement, as shown in FIG. 4, both thefirst and second guidewires 51, 52 subtend into the tubular shaft 43,via the second and third ports 113, 113′, respectively.

Both ports 113, 113′ are preferably situated at a location proximal tothe clutch assembly 48. Further, to aid insertion and passage of theloose guidewire 51, 52 into the respective port 113, 113′, a guidewireloading tool may be used that incorporates a hood or shield positionedover or proximate to the port.

In the configuration of FIGS. 3 and 4, a proximal tube segment 114 ofthe first guidewire tube 95 is disposed longitudinally in the tubularshaft 43. The proximal tube segment 114 defines a proximal passagesegment 115 of the first guidewire passage 90 that is coupled to thesecond port 113. This proximal tube segment 114 is coupled to fourthaccess port 116 that provides access to the lumen through the adapter57. Similarly, in the embodiment of FIG. 4, the second guidewire tube106 includes a proximal tube segment 117 that is disposed longitudinallyin the tubular shaft 43. The proximal tube segment 117 defines aproximal passage segment 115′ of the second guidewire passage 91 that iscoupled to the third port 113′.

In one specific example, as shown in FIG. 19 and 20, both the firstguidewire passage 90 and the second guidewire passage 91 are definedin-part by exterior loose tube segments 110, 111 that span the clutchassembly 48 from the tubular shaft tubular shaft 43 to the transitionportion 46, and permit relative rotation therebetween. Such tubular spansections facilitate advancement of the respective guidewires into thedistal segments of the respective guidewire passages 90, 91, as well asenclose the passages across the span of the clutch assembly. In theembodiment of FIG. 19 the second guidewire tube 106, defining the secondguidewire passage 91, bridges the gap and then extends all the way alongand adjacent to the tubular shaft 43. As mentioned, a distal segment 107of the second guidewire tube 106 is mounted to the exterior surface ofthe transition portion 46, just distal to the clutch assembly forstability (e.g., by adhesive 104). Similarly, the proximal tube segment117 of the second guidewire tube 106 is mounted to the exterior surfaceof the tubular shaft 43, just proximal to the clutch assembly also toenhance stability (e.g., by adhesive 104). In fact, the entire proximaltube segment 117 of second guidewire tube 106 may be adhered to ormelded with the tubular shaft 43 for security thereof during advancementthrough the body vessel.

In accordance with the present invention, however, a loose tube segment110 of the second guidewire tube 106, bridging or spanning the clutchassembly 48 must have a sufficient length, and/or include the ability topermit substantially resistance-free rotational displacement of thestent deployment assembly 45 about the clutch assembly longitudinal axis60.

In a similar manner, as shown in FIG. 19 (as well as the embodiments ofFIGS. 5-7), the first guidewire tube 95 also includes a loose tubesegment 111 spanning the clutch assembly 48 that is also of sufficientlength and characteristics to enable substantially resistance-free,interference-free rotation of the stent deployment assembly 45, aboutaxis 60, relative to the tubular shaft 43. In contrast to the secondguidewire tube 106, the distal tube segment 93 of the first guidewiretube 95 extends into an interior portion of the transition portion 46and the dilator device 47 of the deployment assembly 45.

This loose tube segment 111 of the first guidewire tube emerges from thefirst port 112 to extend exteriorly across the clutch assembly 48. Inthe configuration of FIG. 19, the first guidewire tube 95 enters thetubular shaft 43 at a location proximal to the clutch assembly 48,through a fluid-tight second port 113. A proximal tube segment 114 ofthe first guidewire tube 95 extends through the tubular shaft 43. Thisproximal tube segment 114 defines a proximal passage segment 115 of thefirst guidewire passage 90 that provides access thereto through a thirdport 116.

It will be appreciated that while the first guidewire tube 95 and thesecond guidewire tube 106 have each been described as being essentiallyone continuous tube, they may be defined by multiple components thatcollectively form the respective tubes and their corresponding lumens.For instance, in the embodiment of FIG. 19, the first guidewire tube 95may terminate at the second port 113, and the proximal passage segment115 of the first guidewire passage 90 may be defined by internalstructure of the tubular shaft 43 itself.

In another specific embodiment, as shown in FIG. 20, respective proximaltube segments 114, 117 of the first and second guidewire tubes 95, 106,respectively, extend entirely along the exterior of the tubular shaft43. As mentioned, these proximal tube segments 114, 117 may be mountedor adhered to the tubular shaft for stability during vessel advancement(e.g., adhesive 104).

In another embodiment not shown, the proximal tube segment 117 of thesecond guidewire passage 91 may subtend into the tubular shaft 43, andextend internally therethrough. Similar to those embodiments for thefirst guidewire tube 95, another fluid-tight port may be provided justproximate to the clutch assembly 48 than enables passage into thetubular shaft 43.

FIGS. 21 and 22 illustrate yet another embodiment showing the firstguidewire passage 90 contained entirely within the stent deliverysystem. In this configuration, for example, the first guidewire tube 95may extend through the tubular shaft 43, the clutch assembly 48, andthrough the stent deployment assembly 45. In contrast, in thisembodiment, the distal tube segment 107 of the second guidewire tube 106exits the transition portion 46, distal to the clutch assembly 48,through a fluid-tight fourth port 118. As previously indicated, thedistal tube segment 107 of the second guidewire tube 106 then extendsalong a portion of the exterior of the transition portion and along atleast a portion of the dilator device 47. As shown, the second guidewirepassage 91 also extends through the clutch assembly 48, and through thetubular shaft.

In another embodiment, as shown in FIG. 23, an outer flexible covermember or outer protective boot 139 may further be disposed about theinner protective boot 82. This cylindrical-shaped boot 139 issufficiently long to span and enclose both the first port 112 and thethird port 113. Hence, this section of the first guidewire passage 90 isessentially enclosed by the outer protective boot 139 similar to loosetube segment 111 of the embodiments of FIGS. 5-7. The proximal anddistal portions of the outer boot 139 may be affixed to the outersurface of the tubular shaft 43 and the transition portion 46,respectively, in a manner similar to that of the inner boot 82. Further,the flexibility characteristics and properties should be similar as wellto enable relatively resistance-free rotation of the deployment assembly45 relative to the tubular shaft 43.

This configuration also illustrates an interior first reinforcement tube145 spanning the clutch assembly 145 generally from the first port 112to the third port 113. An interior second reinforcement tube 146 isdisposed proximate to the third port 113 that is spaced-apart from andsmaller in length than the first reinforcement tube 145. The firstreinforcement tube 145 includes an interior pocket 147 formed to receivea centrally disposed stiffening wire 148 that spans the gap from thefirst tube 145 to the second tube 146 where it is also interiorlyreceived. Similar to the embodiment of FIG. 8, this configurationpromotes axial stiffness while permitting relative rotation of theclutch assembly 48 about the longitudinal axis.

A third reinforcement tube 150 is disposed at the intersection or jointbetween the tubular shaft 43 and the middle tube 151. This joint definesthe fourth access port 116 of the proximal tube segment 114. Thisreinforcement tube also promotes axial stiffness during advancement ofthe device. Typical materials of all the reinforcement tubes includeNitinol, stainless steel, PEEK, and carbon fiber, for example. A hypotube 152 may be mounted to the proximal end of the middle tube 151.Furthermore, spaced-apart RO markers 153 are disposed about at thedistal tube segment 93 of the first guidewire tube 95, which facilitatepositioning of the stent delivery assembly 45.

Referring to FIGS. 24 and 25, a double arm catheter 120 is illustratedin which the second guidewire tube 106 is independent in constructionfrom the first guidewire tube 95. In FIG. 24, the second guidewire tube106 and first guidewire tube 95 are connected in a location proximal tothe clutch assembly 48, for example, by a band 120. This allows theguidewire tubes to bend independently of each other.

In FIG. 25, a configuration is shown in which the independent guidewiretubes 95, 106 are connected in two locations proximal to the clutchassembly 46, for example, by a proximal band 121 and a distal band 122.In this configuration, the guidewire tubes can bend independently withinthe space between the connections.

In yet another specific embodiment, as exemplified in FIGS. 26 and 27, asecond rotational clutch assembly 126 may be included that providesadditional rotational dampening, similar to the first clutch assembly48. This second clutch assembly 126 is positioned proximal to the firstclutch assembly 48.

In still another specific embodiment, a torque transmitting device 127may extend through the entire length of the tubular shaft 43 and throughclutch assembly 48 to the stent deployment assembly 45. As shown inFIGS. 27 and 28, this torque transmitting device 127 includes a distalportion mounted to a proximal shoulder 128 of the dilator device 47.This torque transmitting arrangement functions to transmits torque tothe stent deployment assembly 45 for limited control and orientationthereof.

In one embodiment, the torque transmitting device 127 may be provided bya braided inner shaft. In another configuration, as shown in FIG. 27,the torque transmitting device 127 may includes a spiral wire 129 withany cross-sectional shape, such as a round, oval, or rectangular crosssectional area extending through the stent delivery system 40. Thespiral wire 129 will be coupled to a hypotube or stiffening wire of theproximal portion of the tubular shaft 43. The distal end of the spiralwire, as mentioned, will be mounted to the proximal shoulder 128 of thedilator device 47.

In another configuration of FIGS. 26 and 28, the torque transmittingdevice 127 may be provided by a flat wire 130 that reinforces the innerlumen of the inner tube. A nylon liner 131 and a PE liner 132 cooperatewith the flat spring wire reinforcement to transmit torque in onpreferred direction.

Referring now to FIG. 29, there is shown yet another specific embodimentof the clutch assembly in accordance with the present invention. In thisspecific arrangement, the clutch assembly 48 includes an outer flexiblemember 182 coupling the distal portion of the tubular catheter shaft 43to the proximal portion of the tubular transition portion 46, as well asincluding an inner flexible member 172 coupling the distal portion ofthe proximal tube segment 114 to a proximal portion of the distal tubesegment 93, the latter of which cooperate to define a portion of thefirst guidewire passage 90 of the delivery system 40.

In accordance with this specific embodiment of the present inventiveclutch assembly 48 of FIG. 29, one or both of the outer flexible member182 and the inner flexible member 172 may be provided by a woundstructure, disposed relatively co-axial to one another. Each woundstructure must be capable of permitting relatively interference-freerotational displacement between the outer tubular catheter shaft 43 andthe outer tubular transition portion 46, about longitudinal axis 60, aswell as between the inner proximal tube segment 114 and the distal tubesegment 93. More particularly, one end of the outer flexible member 182is fixedly mounted to the end of outer tubular catheter shaft 43 whilethe other opposite end is fixedly mounted to the outer tubulartransition portion 46. Similarly, one end of the inner flexible member182 is fixedly mounted to a distal end of inner proximal tube segment114 while the other opposite end is fixedly mounted to the distal tubesegment 93. For a wound structure, for example, the end coils would thusbe mounted to their respective tubular components.

The outer flexible member 182 may be constructed of a single wound coilor multiple wound coil shaped spring in a nested configuration that iscomposed of a metallic material such as stainless steel, nitinol,platinum, gold, silver or similar materials. Alternatively, the woundmember may be constructed of non-metallic materials such as nylon, PVC,Pebax or similar bio-compatible materials. The wound member 182 may alsobe constructed by winding a flexible material about a mandrel as is wellknown in the art.

Accordingly, such a wound type structure not only permits relativelyinterference-free rotational axial displacement about the longitudinalaxis 60, but also promotes axial stiffness. The adjacent coils 184,hence, must be closely spaced if not in contact with one another when acompressive axial force is applied thereto during advancement.

As best shown in FIG. 29, a cylindrical-shaped outer sealing member 183may be disposed about the outer flexible member 182 to provide a fluidtight seal between the outer surface of the tubular shaft 43 of thedelivery system 40 and the inner lumen 158. Similar to the previouslydescribed embodiments, the inner lumen 158 is utilized as an inflationlumen for an expandable member, such as a balloon, disposed adjacent theclutch 48. This outer protective boot or outer sealing member 183 may beconstructed of a material such as silicone tubing, nylon, urethane,pebax, or similar materials that are biocompatible and capable of beingaffixed to the outer surface of the proximal portion and distal portionof the catheter. The outer sealing member 183 may be a tubular memberthat has been disposed over the outer flexible member 182 oralternatively, the outer flexible member 182 may be dip coated or spraycoated with a selected material to form a fluid tight coating. In yetanother embodiment not shown, an inner sealing member may be disposedabout the outer flexible member 182, wherein one end of the innersealing member would be affixed to the inner wall of the tubular shaft43 while an opposite end thereof would be affixed to the inner wall ofthe tubular transition portion 46 to provide a fluid tight seal betweenthe outer flexible member 182 and the lumen 158 of the delivery system40.

As mentioned, this specific embodiment of the clutch assembly 48 furtherincludes an inner flexible member 171 disposed between the proximal tubesegment 114 and the distal tube segment 93. These co-axially alignedtube segments 114, 93, together with the inner flexible member 171defining a distal portion of the first guidewire passage or lumen 90 ofthe delivery system 40. The inner flexible member 171 may be constructedof a material such as those described previously with regard to theouter flexible member 182. As described above, the inner flexible member171 may be coated with a material such as those described above in orderto maintain a fluid tight lumen disposed between the inner flexiblemember and the outer flexible member. Hence, the annular lumen 158therebetween can be configured as an inflation/deflation lumen for anexpandable member disposed on a distal portion of the catheter. Analternative to coating the inner flexible member is to provide a sleeveof material about the flexible member and affixing the ends of thesleeve to the tubular member disposed on either side of the innerflexible member. Suitable materials of which the sleeves may be formedinclude silicone, PVC, nylon, urethane, pebax and blends thereof.

As shown in FIG. 29 and as mentioned, the opposed ends of the innerflexible member 171 are coupled to the respective ends of the innerproximal tubular segment 114 and the inner distal tubular segments 93.Any conventional mounting techniques can be applied that enable thetubular segments and the flexible member to function as a guidewirelumen. For example, the ends of the inner tubular segments adjacent thelocation of the inner flexible member 171 ends may be flared, neckeddown or otherwise reduced/enlarged in diameter. Alternatively, acomplementary spiral pattern may be formed in the thickness of the endsof proximal/distal tubular segments 114/93 or through the wall of thetubular segments. This configuration would allow the inner flexiblemember 171 to be threaded into the ends of the inner tubular segments114/93, wherein the coating/sleeve 172 may be applied to affix andsecure the inner flexible member 171 to the ends of the respectivetubular segments.

It is further contemplated that the inner flexible member 171 and thecorresponding tubular segments may be constructed from a unitary member.That is, the spiral formation of the flexible section may be formedusing known manufacturing processes such as cutting, laser cutting,water jet cutting and other similar processes.

The sleeve/coating 172 itself may also be fixedly attached to the endsof the respective inner proximal/distal tubular segment 114/93 throughthe use of known attachment methods. For example, the sleeve /coatingmay be melted to the outer surface of the inner tubular segments, orfastened through the application of adhesives and/or mechanicalfasteners such as crimping a band of metallic material.

To substantially reduce or prevent collapse of the outer flexible member182 onto the inner flexible member 171 under a vacuum, such as duringfluid preparation of the device or deflation of the expandable member,the coating and/or the sleeve 172 applied to the inner flexible member171 may further include a stand-off feature 185 formed therein.Referring now to FIGS. 30A through 30D, there are shown exemplarycross-sectional views of alternative embodiments of features 185 thatmay be formed within or upon the outer wall of the coating and/or sleevemember 172. Generally, such stand-off features form a protrusionextending radially outward from an outer peripheral surface of the coils184 of the inner flexible member 172. Any pattern of suchradially-spaced protrusions or features 185 are sufficient so as to forma communication channel 186 between the adjacent protrusions thatextends longitudinally from one end of inner flexible member to anopposite end thereof. Under a vacuum, for instance, the outer flexiblemember 182 may collapse and come to rest upon or abut against theprotrusions 185 while the communication channels 186 formed therebetweenenable fluid communication across the clutch assembly 48, in theinflation /deflation lumen 158. Hence, the entire collapse of the outerflexible member 182 onto the inner flexible member 171 that mightprevent fluid communication in the inflation/deflation lumen 158 isaverted.

Another manner in which to address a collapse of the outer flexiblemember 182 onto the inner flexible member 171 under vacuum is throughthe disposal of an additional central flexible member 271, or as shownin FIG. 31, two central flexible members 271 in the inflation/deflationlumen 158 between the outer and inner flexible members 182 and 171.These central flexible members 271 are disposed longitudinally in thelumen 158, and have a diameter much small than that of the outer andinner flexible members. Each central flexible member 271 includes afirst end, a second end and a lumen disposed therebetween. The innerflexible member(s) 271 may be constructed in the same manner asdescribed with regard to the outer flexible member 182 and the innerflexible member 171 (i.e., as a wound member).

In use, under vacuum, the central flexible member(s) 271 prevent theouter flexible member 182 from touching or becoming stuck to the coating172 applied to the outer surface of the inner flexible member 171.Similar to the features 185 above, during collapse of the outer flexiblemember 182, under vacuum, the inner, outer and central flexible memberwill cooperate to form a communication channel therebetween in the lumen158 that provides sufficient fluid communication.

Referring now to FIG. 32 there is shown yet another embodiment of thecentral flexible member 271′, in accordance with the present invention.As described above, it may be desirable to place an additional flexiblemember within the fluid lumen 158 in order to ensure the fluid lumen 158remains patent during use. In this particular embodiment, a centralflexible member 271′ is formed that is disposed in the fluid lumen 158about the inner flexible member 171. Hence, the central flexible member271′ includes a central lumen sized for receipt of the inner flexiblemember 171 therein. Similar to the inner and outer flexible membersdescribed above, this embodiment of the central flexible member is alsoa wound member. In the embodiment shown in FIG. 32, the central flexiblemember is disposed within the lumen 158 having adjacent coils 188sufficiently spaced-apart in a stretched manner such that there is afluid channel 273 is formed between adjacent coils 188. Thesespiral-shaped fluid channels 273 provide a communication path for whichfluid used for inflation of a balloon disposed distal the clutch 148 mayflow. Additionally, under vacuum, the channels 273 ensure a patent pathfor the fluid to flow within the lumen 158.

As described above, the clutch assembly 48 of the present inventionallows the distal section of the catheter in accordance with the presentinvention to rotate independent of the proximal portion of the catheter.Advantages of the independent inner and outer flexible members includethe ability of the stent deployment assembly 45 of the delivery assembly40 to rotate freely of the tubular shaft 43 thereof as previouslydescribed. Additionally, the design of the flexible members, whileallowing independent rotation of the proximal and distal sections of thecatheter allows an axial force translated longitudinally along thelength of the catheter to be transmitted.

Turning now to FIGS. 33-36, another specific embodiment is illustratedincorporating an axially staggered arrangement of the inner flexiblemember 171 relative to the outer flexible member 182. Accordingly, theclutch assembly 48 essentially consists of an outer clutch device 190and an inner clutch device 191. Typically, the outer clutch device 191,as we the previous embodiments, is the component incurring asubstantially portion of the torsion loads and axial loads duringoperation. The two clutch devices can in fact operate relativelyindependent of one another. Such an axial offset is also beneficial inthat the overall profile can be reduced since the inner and outerflexible members are not nested. Moreover, as will be described, thisarrangement prevents buckling since, using either the elongated shaft 43to support the inner flexible member 171, or the inner distal tubesegment 93 to support the outer flexible member 182. Preferably, bothflexible members should be positioned relatively close to the stentdeployment assembly 45, this should not be limiting. Moreover, while itis preferable to place the outer flexible member 182 closer to the stentdeployment assembly 45, it will be appreciated that the inner flexiblemember 171 may reside closer to the deployment assembly than the outerflexible member.

In this specific embodiment, the proximal portions of both the outer andinner flexible members 182, 171 are fixedly mounted to their respectiveproximal tube segment 114 and the elongated shaft 43, respectively,through a respective support ring 192, 193. Such rings provideadditional axial support to the corresponding flexible members at theirproximal ends as well as providing a means for mounting the coiledmembers to their respective tube segment and elongated shaft.

In contrast, in this configuration, an opposite distal end of the outerflexible member 182 and the inner flexible member 171 is not affixed tothe respective tubular distal tube segment 93 and transition portion 46.As best viewed in FIGS. 37 and 38, each proximal portion of thetransition portion 46 and the distal tube segment 93 includes an inwardtaper portion 194, 195 that is coupled to a respective inner supportshaft 196, 197 sized to axially pass through the respective flexiblemember 182, 171 and terminates at a location proximal thereto. Theseinner support shafts not only provide additional lateral stability, butalso provide support upon which each respective flexible member canrotate about.

Accordingly, both the outer clutch device 190 and the inner clutchdevice 191 permit limited axial displacement between the respectiveshafts or tube segments that they associate with. During advancement ofthe delivery system 40 through a body vessel, compressive axialdisplacement will be limited when the distal end of the respective outerflexible member 182 and the inner flexible member 171 abut and engagethe respective taper portions 194, 195. Accordingly, the taperedportions 194, 195 must be sized and dimensioned to prevent slippage ofthe distal ends of the respective flexible members 182, 171 distallybeyond the tapers.

In contrast, during retraction of the stent delivery system 40 from thebody vessel, it is the corresponding protective sleeve or boot 188, 172that substantially bears the tensile loads. Since the outer clutchdevice 190, as mentioned, is subject to more significant torsion andaxial loads under operation, the outer protective boot 183 is preferablyconfigured to be more durable than that of the inner protective boot172. Accordingly, a more durable material, such as a Pebax or the likeis selected to withstand the twisting and tensile loads it will endureduring use. Moreover, the boot is more loosely fit about thecorresponding outer flexible member 182 to enable more significantrelative rotational displacement. In contrast, the inner protective boot172 may be composed of a silicon material or the like that is thinnerand more form fit around the inner flexible member 171.

It is further contemplated that an additional stiffening member may beincorporated in all these embodiments, such as the inner support shaftsof the embodiments of FIGS. 33-38, longitudinally extending acrosseither the inner or outer flexible member, or both, to enhance thetransmission of longitudinal or axial forces. The additional member maybe in the form of an additional flexible member as described above, oralternatively may be strictly a stiffening element constructed of alongitudinal member.

In accordance with the present invention, the flexible members embodiedin the form of a wound member may be disposed in either a clockwise,counterclockwise orientation or in a combination of either of the twoorientations. Further, the wound flexible members may be provided with avariety of pitches and torsion rates, although all must permit rotationabout their longitudinal axis with very small rotational forces.

The invention is susceptible to various modifications and alternativeforms, and specific examples thereof have been shown by way of examplein the drawings and are herein described in detail. It should beunderstood, however, that the invention is not to be limited to theparticular forms or methods disclosed, but to the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the claims.

1. A stent delivery system for delivering and deploying a radiallyexpandable stent at a strategic orientation and location in a bodyvessel, said delivery system comprising: an elongated shaft; a stentdeployment assembly including a proximal transition portion associatedwith a dilator device adapted for radial expansion from a non-expandedcondition to a radially expanded condition, said dilator deviceconfigured to retain said stent in the non-expanded condition; and arotational clutch assembly configured to rotatably mount the transitionportion to a distal portion of the elongated shaft such that saiddeployment assembly is substantially torsionally isolated from saidelongated shaft.
 2. The stent delivery system according to claim 1,wherein said clutch assembly is adapted to transmit compression forceslongitudinally along the distal portion of the elongated shaft to thedeployment assembly during advancement of the elongated shaft throughthe body vessel.
 3. The stent delivery system according to claim 2,wherein said clutch assembly includes an inwardly tapered shoulderportion coupled to one of a distal end of the elongated shaft and aproximal end of the transition portion, said clutch assembly furtherincluding a neck portion extending from said tapered shoulder portion,said neck portion being formed and dimensioned for sliding rotationalreceipt into an opening at the other of the tubular transition portionand the elongated shaft for rotational receipt thereof.
 4. The stentdelivery system according to claim 1, further including: a flexibleprotective boot device extending circumferentially over the clutchassembly having one end secured to the elongated shaft and an oppositeend secured to the transition portion such that a fluid-tight seal isformed while still enabling relative rotation between the elongatedshaft and the deployment device.
 5. The stent delivery system accordingto claim 1, further including: said stent deployment assembly definingat least a portion of a first guidewire passage therethrough, said firstguidewire passage being sized and dimensioned for sliding receipt of afirst guidewire disposed in said body vessel.
 6. The stent deliverysystem according to claim 5, further including: a second guidewirepassage extending along at least a portion of said stent deploymentassembly, and terminating strategically along the dilator device of saidstent deployment assembly, said second guidewire passage being sized anddimensioned for sliding receipt of a second guidewire disposed in saidbody vessel, and said second guidewire passage being off-set from saidfirst guidewire passage such that during advancement along said firstand second guidewires in the body vessel, said deployment assembly willbe caused to rotate into alignment with the position of the secondguidewire relative to the first guidewire.
 7. The stent delivery systemaccording to claim 6, further including: a distal guidewire tube segmentdefining a distal segment of said second guidewire passage, said tubesegment being secured to the transition portion for rotation thereofabout the longitudinal axis of the deployment assembly, and having adistal end terminating along an exterior of said dilator device.
 8. Thestent delivery system according to claim 7, wherein a distal portion ofsaid distal guidewire tube segment being disposed between the stent andthe dilator device in the non-expanded condition.
 9. The stent deliverysystem according to claim 2, wherein said clutch assembly includes apair of opposed contact elements disposed in opposed relationship to oneanother, one contact element being associated with the elongated shaftwhile the second contact element being associated with the transitionportion such that during said advancement of the elongated shaft throughthe body vessel, the contact element are moved into compressive mutualcontact with one another to transmit axial compressive forces from theelongated shaft to the transition portion.
 10. The stent delivery systemaccording to claim 9, wherein said clutch assembly includes a firstsupport tube associated with the elongated shaft, and a second supporttube associated with the transition portion, each the first and secondsupport tube having respective end portion substantially in opposedrelationship to one another, each end portion supporting one of saidcontact elements in opposed relationship to one another.
 11. The stentdelivery system according to claim 10, wherein said clutch assemblyfurther includes an elongated stiffening element extending substantiallylongitudinally thereacross, one end of said stiffening element beingdisposed in a distal pocket defined in part by a distal end wall of thetransition portion, and an opposite end of said stiffening element beingdisposed in a proximal pocket defined in part by a proximal end wall ofthe elongated shaft such that during said advancement of the elongatedshaft through the body vessel, one end of the stiffening elementcontacts the distal end wall and the opposite end of the stiffeningelement contacts the proximal wall to transmit axial compressive forcesfrom the elongated shaft to the transition portion.
 12. The stentdelivery system according to claim 11, wherein said clutch assemblyincludes a first support tube associated with the elongated shaft anddefining said distal pocket, and a second support tube associated withthe transition portion and defining said proximal pocket, each the firstand a second support tube having respective end portion substantially inopposed relationship to one another.
 13. A rotational clutch assemblyfor a stent delivery catheter for delivering and deploying a radiallyexpandable stent at a strategic orientation and location in a bodyvessel, said delivery catheter including an elongated shaft and adilator device adapted for radial expansion from a non-expandedcondition to a radially expanded condition, said dilator deviceconfigured to retain said stent in the non-expanded condition, saidclutch assembly comprising: a tubular transition portion having a distalend mounted to said dilator device, and a proximal portion rotatablycoupled to the distal end of said elongated shaft at rotational jointfor substantially free rotation about a longitudinal axis thereofrelative to said elongated shaft such that said dilator device issubstantially torsionally isolated from said elongated shaft, and a pairof opposed contact elements disposed in opposed relationship to oneanother, one contact element being associated with the elongated shaftwhile the second contact element being associated with the transitionportion such that during said advancement of the elongated shaft throughthe body vessel, the contact elements are moved into compressive mutualcontact with one another to transmit axial compressive forces from theelongated shaft to the transition portion.
 14. The rotational clutchassembly according to claim 13, wherein said rotational joint includesan inwardly tapered shoulder portion coupled to one of a distal end ofthe elongated shaft and a proximal end of the transition portion, saidrotational joint further including a neck portion extending from saidtapered shoulder portion, said neck portion being formed and dimensionedfor sliding rotational receipt into an opening at the other of thetubular transition portion and the elongated shaft for rotationalreceipt thereof.
 15. The rotational clutch assembly according to claim13, further including: a flexible protective boot device extendingcircumferentially over the rotational joint having one end secured tothe elongated shaft and an opposite end secured to the transitionportion such that a fluid-tight seal is formed while still enablingrelative rotation between the elongated shaft and the deployment device.16. The rotational clutch assembly according to claim 13, furtherincluding: a first support tube associated with the elongated shaft, anda second support tube associated with the transition portion, each thefirst and second support tube having respective end portions disposed insubstantially opposed relationship to one another, each end portionsupporting one of said contact elements in opposed relationship to oneanother.
 17. The rotational clutch assembly according to claim 16,further including: an elongated stiffening element extendingsubstantially longitudinally across the rotational joint, one end ofsaid stiffening element being disposed in a distal pocket defined inpart by a distal end wall of the transition portion, and an opposite endof said stiffening element being disposed in a proximal pocket definedin part by a proximal end wall associated with the elongated shaft suchthat during said advancement of the elongated shaft through the bodyvessel, one end of the stiffening element contacts the distal end walland the opposite end of the stiffening element contacts the proximalwall to transmit axial compressive forces from the elongated shaft tothe transition portion.
 18. The rotational clutch assembly according toclaim 17, further including: a first support tube associated with theelongated shaft and defining said distal pocket, and a second supporttube associated with the transition portion and defining said proximalpocket, each the first and second support tube having respective endportions disposed in substantially opposed relationship to one another.